Printed circuit boards are extensively used in the electronics industry and they are usually provided with preformed holes to receive the leads of various components to be electrically interconnected by the printed circuitry. It has been found that such electronic components can be quickly and economically inserted into printed circuit boards through the use of automatic equipment which has been programmed to rapidly place the leads of the components into the proper holes. The leads that are provided on the components are of a generally standard length and are usually much longer than needed after the component has been placed into the board. With the automatic equipment, these excessive length leads are located in a position relative to the board and are then inserted through the holes. The equipment will then automatically trim and clinch the leads and careful trimming and clinching assures proper contact between the lead and the printed circuit board and also removal of excess wire thereby providing accurate, reliable and neat connections.
Although the cut and clinch mechanisms presently used effectively clinch the electronic component against the printed circuit board and also effectively trim the excess leads, I have found that the operation sometimes fails because of a mis-alignment between the lead-in wire and the cut-clinch mechanism. Good cutting and clinching requires that the lead-in wires be inserted normal to the circuit board and from time to time, a wire becomes bent from that position prior to working upon it. Thus, the cut-clinch mechanism will not engage the wire and perform its function.
(1) Field of the Invention
The present invention relates to equipment for securing wire terminals to workpieces and particularly to equipment for inserting and securing electronic components to printed circuit boards by cutting and clinching the lead wires of such electronic components.
(2) Prior Art
Component inserters of the type generally under consideration in the present invention are described, for example, in the U.S. Pat. Nos. to Romeo, 3,429,170 and Woodman, 3,986,533. These patents disclose inserters that are rotatable and reciprocable upon an axis and they include a pair of reciprocal cutting and clinching elements that are mounted for angular rotation to orient the elements in accordance with the orientation of the leads passing through the board. When the inserter is reciprocated on its axis, the cutting elements move to shear unnecessary lengths of wire that extend through the circuit board and also crimp a small portion of the wire against the circuit board for securing the component and for the establishment of an electrical connection. Neither of these patents disclose a mechanism for detecting whether or not the lead-in wires which are inserted through the printed circuit board are actually in place to be shorn and clinched. In the U.S. Pat. to Taguchi, No. 4,165,557, a mechanism is disclosed for trimming and securing parallel lead-in wires of electronic components and sensing whether each lead-in wire is disposed within the mechanism. In that patent, sensing is accomplished prior to the cutting and clinching by contact of the lead-in wires with electrical sensors that are disposed within the cut-clinch unit.